Complet break down of makitia demo hammer

Beware for all not all parts are more available, there is no oil used only Grease
Service Pack 1617000036 for Bosch Power Tool eReplacement Parts

first ordernumber 931848 lubrication necessary it has its working hours on it.
parts to change in priority
1 x 944-927 , 949457Z , 956-960 , 944-936 , 956-965 ,
999032 , 956-996 , 944-928
the important thing is that the machine is airtight at the front so as not to burn the O-rings through the air and incoming dirt friction look the orings good and if the lock bolt on the front feel not smooth replace that also and every oil seal you can find its different what should neccesary but that the tool runs with thick and dirt beaten oil . solvent clean the hard metal parts and replace if there are grooves on or cracks
Hitachi PH 65A Demo Hammer Parts

Jack up car put on stands remove exhaust if it crosses under sump remove all the screws or nut bang side of sump with a rubber hammer to break seal,clean off old sealer.

Check the brushes first. If they are worn or sticking they could cause this.

If the brushes are fine and not worn down then it is most likely the electronics/ variable speed module.

Go to http://www.makitatools.com/en-us/Modules/Home/Default.aspx, put your model number in search box in the top right. Two models of the HM1500 will come up, select yours and open the owner's manual. Find the paragraph labeled 'Lubrication' and follow it precicely. Demo hammers are very picky about what type of grease they use and how much. Too thick and they won't work, too thin and they won't lubricate properly and the parts inside are very expensive to replace. Same applies to how much to use.

Your hammer has brushes that push away from the armature when they wear past a certain point. At this time you could buy the service kit that includes most parts including grease to get your going again. The link below will give you an idea of the parts included in the kit. If however you store your hammer more than use it, you could pull the lower half and lube it. You can just order Bosch grease. If your hammer is used constantly / heavy / hot climate, you can increase the life of the tool by greasing more often. Most damage is done by using long cord or generator with too high or too low voltage. Good luck

http://www.ereplacementparts.com/service-pack-pi-81738.html

Worked at a tool rental store while attending college and learned some tricks from the old-timers. To extend the life of flexible blades such as the one used on floor tile removers, use a second shorter blade on top of the longer blade (double blades). The shorter backup blade tends to absorb the extra force making the longer blade last longer before breaking. The length of the shorter backup blade is trial and error, however start with about 3/4 to one inch back from longer. The wide chipper bits tends to break also. The wider the bit, faster to break. No matter what size hammer. Has to do with the bit hitting the stop on the forward motion. Some older chipper hammers that had rubber or spring loaded bit stopper would prevent wide chipper from breaking so fast. Good luck

Demo hammers do not oil/grease the bit. The grease in the tool is to lubricate and cool the parts in there doing the hammering. The bit should have grease on the end going into the hammer to make it work in the tool better and make it easier to take out when you are done. You have to put the grease on the bit yourself.

rockworth powertask demo hammer needs new trigger how do i get parts

if pneumatic, it needs to be oiled with some air tool oil into the air supply nipple, 4 drops a day when used